I can gybe a surfboard 95% of the time using a range of different techniques but a foilboard is very different. I am now using a small board (120cm = 4') and a high lift surf/cruising foil (J-shapes Cruzer) and have lost the ability to surface gybe. I have to stall the board to get off the foil and the board starts to sink as it is pretty low volume. The foil then wants to foil up halfway through the gybe.

What is the easiest gybe to learn?
1. Keep perservering with the surface gybe.
2. Foil downwind and switch feet halfway through the gybe. Some people seem to have both feet forward for a while partway through the gybe.
3. Switch feet early and then carve toe-heel.
4. Carve onto toe-side and then switch feet.
I guess 3. and 4. might be personal preference depending on whether the rider is normal or goofy footed. I am pretty comfortable on either stance.

I was stuck like you did for 30 (or even more) sessions. The pivotal hint (pun not intended) was to learn that switching feet is difficult. Therefore, it goes in progression after being able to carve downwind 180 without foot switch and riding toeside. Certainly, you'll master surface turn even with short board, but it is easier with medium one.

If I’m understanding your question correctly, a surface jibe is gonna be easier than any flying jibe. As far as the flying jibes, I personnally found the footswitch before the jibe to be easier than the footswitch after the jibe.